Railway traffic controlling apparatus



. Sept. 22, 1931. I -v. LEWIS RAILWAY TRAFFIC CONTROLLING APPARATUS Filed June 17, 1926 I INVENTOR;

Patented Sept. 22, 1931 UNITED STATES PATENT OFFICE LLOYD V. LEWIS, F EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIG-NOR TO THE UNION SWITCH. & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION 01' PENNSYLVANIA RAILWAY I TRAFFIC CON TROLLING 'AIPABATU'S Application filed June 17,

5 received from the trackway.

One feature of my present invention is the provision of means for at times supplying the rails of the trackway with un1nterrupted alternating train controlling current and for at other times supplying the rails with alternating train controlling current which is periodically interrupted. The train carried governing means is selectively responsive to the interrupted or uninterrupted train controlling current in the trackway.

I will describe one form of trackway ap paratus and one form of train governing means embodying my invention, and will then point out the novel features thereof in claims.

showing one form. of train carried govern- 3 lar parts in both views.

In the accompanying drawings, Fig. 1 is a diagrammatic view illustrating one form of trackway apparatus embodying my invention. Fig. 2 is a diagrammatic view ing means suitable for oo-operation with the trackway apparatus illustrated in Fig. 1 and also embodying my invention.

Similar reference characters refer to simi- 'Referring first to Fig. 1, the reference characters 1 and 1* designate the track rails of a stretch of railway track over which trafiic normally moves in the direction indicated by the arrow. These rails. are divided by means of insulated joints 2 into a plurality of successive track sections A-B, B--C, etc. Each track section is provided with a track transformer designated by the reference character T with an appropriate distinguishing exponent and having a secondary 4 connected across the rails adjacent the exit end of the corresponding section through the usual im edance 6. The primary 5 of each transtormer T is at times supplied with alternating current of one relative polarity or the other from second ary 9 of an associated line transformer designated by the reference character U with an exponent corresponding to the location.

1926. Serial No. 116,608.

The primary 10 of each such transformer U- is constantly supplied with alternating current from a suitable source, such as an alternator M, over line wires 3 and 3. Each track section is also'provided with a polarized track relay designated by the reference character R with an appropriate exponent.

Each track relay R comprises two windings 7 and 8, one of which 7, is connected across the rails adjacent the entrance end of the corresponding section. Winding 8, of each relay R is constantly sup lied with alternating current from secondhry't) of the adi'acent line transformer U. The track reays may be used to control trackway apparatus, not shown in the drawings, in any manner desired.

Each track section is provided with a trackway signal designated by the reference character S with 'an ap ropriate exponent. These signals may be of any suitable form and are here shown as semaphore signals each capable of displaying a proceed, a caution, or a stop indication. The circuits for controlling the signals S form no art of my present invention and are omitte from the drawings for the sake of simplicity. For present purposes itis suflicient to state that each signal is controlled in such manner that when the corresponding section is occupied the signal indicates stop, when the corresponding section is unoccupied and the section next in advance is occupied,the sig-.

nal indicates caution, and when the corresponding section and the section next in ad-' .Vance are both unoccupied the signal indicates proceed.

Associated with each signal S is a pole changer and a circuit controller desi nated by the reference characters W and respectively, with exponents corresponding to the location. Each pole changer W occupies one position when the associated signal indicates stop and another position when the signal indicates caution or proceed. Each circuit controller X is closed only when the associated signal indicates caution or proceed.

Each track section is further provided with. a coding relay designated by the refand 21 back to secondary 9 of transformer U. This circuit is closed only when signal S indicates caution or proceed and when relays R and Q are both de-energized. Under these conditions current is supplied to relay Q energizing the relay, and opening its back contacts. When this happens the circuit just traced for relay Q is inter rupted so that the rela again opens to close its back contact an a second impulse of energy is supplied to the relay. This operation continues, and the relay is intermittently energized, as long as the signal S indicates caution or proceed and relay R remains de-energized.

Primary 5 of transformer T is connected with secondary 9 of transformer U overback contact 11 of relay Q and pole changer W It follows that when signal S indicates caution or proceed, alternating current of one relative polarity, which I will call normal relative polarity, is su plied to the rails of section A-B, and that when signal S indicates stop, current of the other relative polarity, which I will call reverse relative polarity, is supplied to the rails of this section. It should also be pointed out that when relay Q, is operating to periodically open back contact 11 thereon, the primary circuit for transformer T is periodically opened, so that the current supplied to the rails of section A- -B is periodically interrupted.

The supply of alternating current to each of the remaining transformers T is controlled by the associated coding relay Q, in the same manner as just explained in connection with the control of transformer T by relay Q As shown in the drawings, the section to the right of point C is occupied b a train indicated diagrammatically at V. elay R is therefore de-energized and signal S indicates stop, so that pole changer W is reversed. Current of reverse relative polarity is therefore supplied without interruption to the rails of section B--C by transformer T Relay B is energized in the reverse direction so that back contact 14 thereon is open and relay Q is continuously de-energized. The circuit for relay QP is also open at circuit controller X The alternating current supplied to the rails of section B-C is therefore uninterrupted. Signal S indicates caution so that circuit controller X is closed and current of normal relative polarity is sup lied to the rails of section AB. Relay Etis therefore energized in the normal direction and the circuit for relay Q is interrupted at back contact 14 of relay R Back contact '11 of relay Q is therefore continuously closed, so that the rails of section A-B are supplied with uninterrupted alternating current. Signal S indicates proceed so that the rails of the section to the left of point A are supplied with alternating train controlling current of normal relative polarity.

The section to the left of point A is occupied by a second train indicated diagrammatically at V. The track relay for this section is therefore de-energized so that relay Q is operating and interrupted alternating current is su plied to the rails of the section to the le t of point A. When this train enters section AB, relay R will become de-energized, completing the circuit for relay Q, and causing the primary circuit for transformer T to be periodically opened. The train will therefore receive interrupted alternating current as it proceeds through section B-C. When the train enters section B-C, relay R will become deenergized, but the circuit for relay Q is open at circuit controller X so that relay QP will remain de-energized and the alter nating current supplied to the rails of section B-C will be uninterrupted. When the train enters the section to the right of point C it will be deprived of train controlling current by the shunting effect of the wheels and axles of train V.

For the .purpose of controlling the train carried governing means in accordance with the train controlling current in the trackway the train V is provided with a receiver designated in general by the reference character P and comprising two magnetizable cores 22 and 22 carried on the train in advance of the forward axle and located in inductive relation with the two track rails 1 and 1* respectively. Core 22 is provided with a winding 23 and core 22is provided with a similar winding 23, the windings 23 and 23 being connected in series in such manner that the voltages induced therein by. alternating currents flowing in o posite directions in the track rails at an instant are additive.

Referring now to Fig. 2, the windings 23 and 23 are connected, through a condenser 25, with the primary 24 of'an auto-transformer L. The windings 23 and 23" and l the condenser 25 of the pick-up circuit N are tuned to series resonance at the frequency of the train controlling current in the trackway. The secondar of the auto-transformer L is tuned to para lel resonance at the frequency of'the train controlling current with condenser 26. The resonant voltage at the.

terminals of condenser 26 is amplified by two electron tube amplifiers E and E The filaments of these tubes are connected in series with a; ballast lamp 29 and two control resistances 28 and 30 and are supplied with current from a suitable source such as a battery 73. The secondary of the autotransformer L is connected across the grid and filament of tube E through the biasing resistance 30 and a comparatively high resistance 27. The purpose of resistance 27 is to limit the load on the resonant circuit when the voltage across condenser 26 is higher than the voltage drop in the filament circuit across resistance 30, as in that case the grid would be positive with respect to the filament during a port-ion of each cycle, permitting current to flow from filament to grid in shunt with condenser 26. The plates of the electron tubes E and E are provided with a comparatively high unidirectional electromotiw force from a suitable source such as the high potential winding 32 of a. dynamotor comprising a low potential winding 31 and a field coil 3 1 constantly supplied with energy from battery 7 3. The high potential winding 32 has its positive terminal connected with the plate of tube E through a reactor 33. The positive terminal of the winding 32 is also connected with the plate of tube B through a similar reactor 37. The plate of tube E is also connected through a condenser 34 and an adjustable resistance 36 with the negative terminal of the battery 73. The grid of tube E is connected with a point a on resistance 36 and it will therefore be plain that the tubes E and E and the associated apparatus comprise an amplifier of the well known choke coil coupled type.

The energy delivered b tube E is supplied to the primary 38 o a transformer Y which is connected across the plate and filament of this tube. A stopping condenser 40 is connected in series and a tuning condenser 41 is connected in parallel, with the primary 38 of transformer Y. Condenser 40 serves to choke out from transformer Y currents of a lower frequency, while condenser 41 serves to by-pass currents of higher frequency, than that of the train controlling current. The secondary 39 of transformer Y supplies energy to a relay D having one terminal connected with the mid-point b of secondary 39 and, the other terminal connected with the extremities of this winding through rectifiers 42 and 43.

It follows that alternating current flowing in the track rails 1 and l creates in the pick-up circuit N an alternating current, which is amplified by devices E and E and creates in the secondary of transformer Y an alternating current which is changed to a uni-directional current by the rectifiers 42 and 43 and serves to energize the relay D.

The auto-transformer L operates as a filter to prevent energization of relay D by stray currents of a frequency different from that of a train controlling current. As hereinbefore stated the secondary of the auto-transformer L is tuned to parallel resonance at the frequency of the train controlling current by condenser 26 so that at this frequency the impedance of the condenser and the transformer secondary in parallel, as measured between their common terminals, will be a maximum and equivalent to a high noninductive resistance. It follows that the impedance as measured across any portion of the transformer will likewise be non-induc-- tive. For example, I will assume that the primary winding 24 contains one-fifth of the total number of turns in the auto-transformer. The voltage across the primary 24 will therefore be one fifth of the total voltage across the auto-transformer and the current required to excite coil L will be five times as great as would be the case if this current flowed through all turns of the coil. It follows that the input impedance as measured across the terminals of primary 24 is equivalent to a low non-inductive resistance at the resonant frequency, and that coil L and condenser 26, have the same effect on the pick-up circuit, at this frequency, as if a non-inductive resistance were inserted in series with the pick-up circuit. The impedance of the remainder of the circuit N, comprising coils 23, 23 and condenser 25 is likewise equivalent to a non-inductive resistance at this frequency. The load resistance, comprisin primary 24, is made equal to the internal resistance of windings 23 and 23* in circuit N. It follows that, under these conditions optimum energy is transferred from the pick-up circuit to the filter circuit and it also follows that the voltage across the terminals of condenser 26 will be the optimum because the energy supplied to coil L is an optimum.

Returning now to relay D, it is to be noted that when relay D is energized, current flows from battery 73, through wires 51 and 52, front contact 53 of relay D, wire 54, winding of relay K, and wires 56 and 57 back to battery 7 3. Relay K is therefore energized only when relay D is energized. .VVhen relay D is de-energized current flows from battery 73 through wires 51 and 52, back contact 53 of relay D, wire 58, winding of relay J, and wires 59, 56 and 57 back to battery 73. It follows that when relay D is continuously de-energized relay K also is continuously de-energized; when relay D is continuously de-energized relay J is continuously energized; and when relay D is operated intermittently, as when the train occupies a stretch of track which is being supplied with interrupted alternating current, relays J and K are energized alternately. Relays J and K have slow-releasing characteristics so that they hold their front contacts closed during the intervals between successive energizations and the front contacts of both c through section A-B. Relays J and K are then both picked up, and current flows from battery 73, through wires 51, 60, 61 and 62, front contact 44 of relay K, wire 63, front contact 46 of relay J, wire 64, lamp 48 and wire 65, front contact 47 of relay J, wire 66, front contact 45 of relay K, and wires 71, 72 and 57 back to battery 73. Under these conditions lamp 48 is lighted to indicate proceed.

\Vhen the train enters section B-C the alternating current continuously suppliedto the rails energizes relay D continuously."

Relay K is therefore closed but relay J is open and current flows from battery 73, through wires 51, 60, 61 and "62, front contact 44 of relay K, wire 63, back contact 46 of relay J, wire 67, lamp 49, wire 68, back contact 47 of relay J, wire 66, front contact 45 of relay K, and wires 71, 72 and 57 back to battery 73. Lamp 49 is therefore lighted to indicate caution.

When the train enters the section to the right of point C the supply of train controlling'current to the train is interrupted so that relay D becomes de-energiied, picking up relay J, but allowing relay K to open. Current then flows from battery 73, through wires 51, 60, 61 and 62, back contact 44 of relay K, wire 69, lamp 50, wire 70, back contact 45 of relay K, and wires 71, 72 and 57 back to battery 73. Lamp 50 is therefore lighted to indicate stop.

The lamps 48, 49 and 50 as here shown comprise a cab signal for giving the engineman visual indication of traffic conditions in advance, but this cab signal is merely shown for purposes of explanation and may be replaced by any suit-able train governing means. It will be noted that one indication is received on the train when the rails are supplied with interrupted alternating train controlling current, that a second indication is received on the-.train when the rails are supplied with 'uninterrupted alternating train controlling current, and that a third indication is received on the train when the supply of train controlling current to the rails is discontinued.

Although I have herein shown and de scribed only one form of trackway apparatus and only one form of train carried governing means embodying my invention, it

is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention what I claim is:

1. Railway trafiic controlling apparatus comprising a section of railway track, means for at times supplying alternating current continuously to the rails of said section in series, means for at times periodically interrupting said alternating current, amplifying apparatus on the train receiving energy from the track rails, a train carried relay, a rectifier interposed between said amplifying apparatus and said train carried relay, two slow acting relays one controlled by a front contact of said train carried relay and the other controlled by a back contact of said relay, a first governing device controlled by a front contact on'each said slow acting relay, a second governing device controlled by a front contact on one of said slow acting relays and b a back contact on the other said relay, an a third governing device controlled by a back contact on such' one slow acting relay.

2. In combination, a stretch of railway track, means for at times su plying alternating current to the rails of said stretch, an auto transformer having a secondary tuned to resonance at the frequency of such current, train governing means controlled by energy delivered by said secondary, a 1

receiver comprising two coils in inductive relation with the two track rails respectively the internal impedance of said coils in series being equal to the resonant impedance of the primary of the auto transformer, and a circuit includin said coils and said primary in series ancf tuned to series resonance at the frequency of said current.

3. In combination, a stretch of railway track, means for at times su plying alternating current to the rails 0? said stretch, a pick-up circuit receiving energy from the track rails, an electron tube amplifier receiving energy from the ick-up circuit, a filter interposed between the pick-up circuit and the amplifier, a high resistance interposed between the filter and the amplifier to prevent oscillation of the amplifier upon failure of the electron tube, and train carried governing means controlled by energy delivered by said amplifier.

In testimony whereof I aflix my signa- 

